Devices for separating grain mill particulates have been developed to sift and sort different sized particulates into fine and coarse classifications. Gyratory sifters, called plansifters, used for sifting dry, free flowing materials have a number of sieve decks superimposed one upon another which function to provide large capacity separation of materials in different particle size classifications. These sifters are utilized for purifying flour, grains and cereal flakes by removing large objects and particles from the desired fine particles preparatory to packaging. Examples of these types of sifters are disclosed by W. L. Mock and W. Taylor in U.S. Pat. No. 3,422,955 and A. Keller in U.S. Pat. No. 5,538,139. The sieve decks or sieve boxes in sifters have screen or mesh sizes from fine to coarse. The sifters have centrifugal drives which import circular motions to the sieve boxes. The fine particulates flow through the screens and settle on pans. The particulates move along the pans to exit openings in the sides of the sieve boxes. The coarse particulates move along the top of the screens to discharge channels along the sides of the sieve boxes.
Many ground grain particulates have poor sifting properties due to high humidity and particle size. The screens clog up with particulates which reduces the sieve output of the sifters. Screen cleaners have been incorporated in sieve boxes to clear particulates from the screens during the sifting operation of the sifter. The screen cleaners are free moving objects, such as balls, rings, and spoke structures that randomly contact the screens to separate particulates from the screens. Examples of screen cleaners used in sieve boxes are found in the following U.S. patents. C. S. Pennington in U.S. Pat. No. 3,565,251 discloses a sieve assembly having a box frame supporting a sieve structure and a carrier for sieve cleaners. The sieve cleaners are rubber-like balls that are free to move in compartments in the carrier to clear articles from the sieve structure and carrier. The balls have limited contact with the sieve structure as only a relatively small convex curved surface of each ball engages the sieve structure. A. M. Hukki in U.S. Pat. No. 5,051,171 discloses a self cleaning system for vibratory screens that uses one-piece screen cleaning elements shown as cylindrical or ring members. The screen cleaning elements are free to move and bounce below the screen during gyration of the separator machine. The cleaning elements contact the screen to separate materials from the screen and clear materials from a perforated pan. A. Keller in U.S. Pat. No. 5,538,139 discloses a sieve box with one-piece sieve cleaners that clean the sieve screen and clear product from a pan. The sieve cleaners have a number of arms, a wobble foot, and knobs, bristles or cleaning ribs on the arms for removing product from the sieve screen during gyration of the sieve box.